1. Field of the Invention
The invention relates to a locking hydraulic brake system. More particularly, the invention relates to locking mechanisms for installing between a master cylinder and a brake line. The invention further relates to a locking master cylinder assembly.
2. The Prior Art
Locking hydraulic brake systems or parking brakes according to embodiments of the invention may be used in various types of vehicles having hydraulically actuated brakes, for example automobiles, motorcycles, all-terrain vehicles and snowmobiles. A locking mechanism and a locking master cylinder assembly according to embodiments of the invention are particularly suited for use with a front or rear brake assembly of a motorcycle.
A motorcycle front brake system typically includes a hand-operated lever disposed on the right handlebar grip, along with the throttle. This lever operates a piston within a master cylinder assembly which is also secured to the right handlebar. Squeezing the brake lever forces hydraulic fluid from the master cylinder through a “banjo bolt” fitting and brake line to the front brake caliper to operate the brake. When the brake lever is released, the hydraulic fluid is allowed to flow back to the master cylinder, and the brake is released.
Existing motorcycle front brake systems generally do not include any type of locking mechanism, and accordingly when an operator is stopped on an incline, the operator must maintain pressure on the brake lever with his or her right hand to prevent the vehicle from rolling backward, while simultaneously twisting the throttle with the right hand to warm the engine. This is a difficult procedure and the motorcycle may roll backwards (“rollback”) if not performed properly. Additionally, using the rear brake to hold the motorcycle has the disadvantage of requiring the operator to balance the bike with just one leg as the other foot must be used to depress the rear brake foot pedal used to actuate the rear brake.
A number of devices and systems for locking a brake on a vehicle such as a motorcycle, all-terrain vehicle or snowmobile are known. The following references, the disclosures of which are hereby incorporated by reference, relate to mechanisms for locking a vehicle brake in an engaged state.
U.S. Pat. No. 5,327,724 Tribuzio et al. shows a lockable master cylinder having a reversible electric motor for locking the piston in a rest or working position to keep the vehicle brake applied.
U.S. Patent Application Publication No. 2006/0076197 to Ishida, U.S. Pat. No. 6,450,301 to Iizuka et al. and corresponding Japanese Patent No. JP 2002/079981 A to Iizuka et al., each show a locking motorcycle rear brake system which requires an additional caliper to serve as a parking brake for the motorcycle rear wheel.
U.S. Pat. No. 3,498,361 to Carlson and U.S. Pat. No. 5,857,385 to Takeuchi describes devices for locking a lever which operate a cable-type mechanical brake.
U.S. Patent Application Publication No. 2006/0071542 to Lichtensteiger et al. shows a handlebar master cylinder assembly with a park pawl which engages a bracket connected to the master cylinder body to maintain the brake lever locked in an applied position. The park pawl flexes to compensate for hydraulic fluid temperature changes and maintain proper brake pressure.
Japanese Patent No. JP 411-189189 to Sekiya shows a parking brake device for a hydraulic motorcycle brake. The device has a sliding piston mounted in a cylinder adjacent the brake lever and an end of the piston contacts an end surface of the brake lever to set the parking brake.
Japanese Patent No. JP2003/112684 A to Igarashi shows a motorcycle parking brake with a brake lock lever mounted on the left handlebar for braking a drum brake of a motorcycle's rear wheel.
U.S. Pat. No. 4,041,798 to Shinozaki et al. shows a pawl and cam mechanism for locking a foot pedal which actuates a motorcycle rear brake.
The devices and systems for locking a vehicle brake as disclosed in the references cited above exhibit several deficiencies. In particular, the known systems are complicated and costly and are not easily adaptable to a vehicle's original equipment manufactured (OEM) braking system. Some of the known locking systems require additional brake calipers or electronics and solenoids. In addition, the known devices generally require substantial modification to a conventional vehicle brake system to implement.
Accordingly there exists a need for a simple and inexpensive locking brake mechanism which can be easily installed on an existing vehicle hydraulic brake system, such as a motorcycle front or rear brake system. Additionally, the need exists for a locking or parking system comprising a simple mechanical device which can be added to an existing motorcycle front or rear brake system as an aftermarket item or supplied as original equipment.